CN108292919A - Switching circuit and power-supply system - Google Patents

Abstract

In the switch circuit (110) for a vehicle, in each of the first main transistor (Tr1) and the second main transistor (Tr2), on/off between the drain electrode and the gate electrode depends on the relationship between the gate electrode and the source electrode. to switch between voltages. A first surge protector (1) is connected between drain electrodes of the first main transistor (Tr1) and the second main transistor (Tr2). The first surge protector (1) maintains the voltage applied to the first surge protector (1) below a first predetermined voltage. A sub-transistor (Tr3) is provided between the respective gate electrodes and source electrodes of the first main transistor (Tr1) and the second main transistor (Tr2). The sub-transistor (Tr3) is turned on when the first main transistor (Tr1) and the second main transistor (Tr2) are turned off.

Description

Switching circuit and power system

technical field

The invention relates to a switch circuit and a power supply system.

This application claims priority based on Japanese application No. 2015-224625 filed on November 17, 2015, and uses all the content described in the above-mentioned Japanese application.

Background technique

The switch circuit described in Patent Document 1 has an NPN type bipolar transistor. In a bipolar transistor, the bipolar transistor is turned on or off by adjusting the base voltage based on the emitter potential. When the voltage of the base with respect to the potential of the emitter becomes equal to or higher than a certain voltage, the bipolar transistor is turned on, and a current can flow between the collector and the emitter of the bipolar transistor. When the voltage of the base based on the potential of the emitter becomes lower than a certain voltage, the bipolar transistor is turned off, and no current flows between the collector and the emitter of the bipolar transistor. When the bipolar transistor is turned on, the higher the base voltage based on the emitter potential, the smaller the resistance value between the collector and the emitter.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 5-218833

Contents of the invention

A switch circuit according to one aspect of the present invention is a switch circuit for a vehicle, wherein the switch circuit includes: a transistor circuit including a first main transistor having a first electrode, a second electrode, and a control electrode; The on/off between the first electrode and the second electrode is switched according to the voltage between the control electrode and the second electrode; the first surge protector is connected to the two transistor circuits Between the terminals, the voltage applied to the first surge protector is maintained below the first specified voltage; and the sub-transistor is arranged between the control electrode and the second electrode of the first main transistor, between and turning on when the first main transistor is off.

A power supply system according to one aspect of the present invention includes: the switching circuit described above; and two power storage devices, the positive electrodes of which are connected to the switching circuit.

Description of drawings

FIG. 1 is a schematic diagram showing the configuration of a power supply system in Embodiment 1. As shown in FIG.

FIG. 2 is an explanatory diagram of the operation of a switching circuit without a first surge protector and a sub-transistor.

FIG. 3 is an explanatory diagram of the operation of a switching circuit provided with a first surge protector and a sub-transistor.

4 is another explanatory diagram of the operation of the switching circuit provided with the first surge protector and the sub-transistor.

FIG. 5 is a schematic diagram showing a part of a switch circuit in Embodiment 2. FIG.

FIG. 6 is a schematic diagram showing a part of a switch circuit in Embodiment 3. FIG.

FIG. 7 is a schematic diagram showing a part of a switch circuit in Embodiment 4. FIG.

FIG. 8 is a schematic diagram showing a part of a switch circuit in Embodiment 5. FIG.

FIG. 9 is a schematic diagram showing a part of a switch circuit in Embodiment 6. FIG.

FIG. 10 is a schematic diagram showing an example of a timing chart of a switching circuit.

FIG. 11 is a schematic diagram showing a part of a switch circuit in Embodiment 7. FIG.

FIG. 12 is a schematic diagram of a power supply system in Embodiment 8. FIG.

FIG. 13 is an explanatory diagram of the operation of the switching circuit.

Detailed ways

[Problems to be Solved by the Invention]

In the switching circuit described in Patent Document 1, for example, the positive terminal of the power storage device is connected to the collector of the bipolar transistor, the emitter of the bipolar transistor is connected to one end of the load, and the negative terminal of the power storage device is connected to the other end of the load. One end is grounded. In this case, when the bipolar transistor is turned on, the power storage device supplies electric power to the load via the bipolar transistor, and when the bipolar transistor is turned off, the power supply from the power storage device to the load is stopped.

To turn on the bipolar transistor, by raising the base voltage of the bipolar transistor with respect to the ground potential, the base voltage with respect to the emitter potential is raised. When the bipolar transistor is to be turned off, the base voltage of the bipolar transistor based on the emitter potential is lowered by lowering the base voltage of the bipolar transistor based on the ground potential.

The wiring connecting the bipolar transistor and the load has an inductance component (hereinafter referred to as wiring inductance). While the bipolar transistor is on, current flows through the wiring, and energy is accumulated in the wiring inductance.

When the voltage at the base of the bipolar transistor with reference to the ground potential is lowered to turn off the bipolar transistor, the resistance value between the collector and the emitter of the bipolar transistor increases, and the flow through the distribution The current in the line is reduced. At this time, the wiring inductance lowers the emitter voltage based on the ground potential to maintain the current flowing through the wiring, and maintains the base voltage based on the emitter potential at a constant voltage or more. As a result, a current flows through the bipolar transistor, and the energy accumulated in the wiring inductance is released. When this energy becomes zero, the voltage of the base based on the potential of the emitter becomes lower than a certain voltage, and the bipolar transistor is turned off.

While the wiring inductance maintains the emitter voltage based on the ground potential at a certain voltage or more, the voltage between the gates based on the emitter potential is low, so the gap between the collector and emitter of the bipolar transistor The resistance value between them is large. Therefore, the power consumed by the bipolar transistor is large, and the heat generated by the bipolar transistor is large. Therefore, the temperature of the bipolar transistor becomes high, and the function of the bipolar transistor may decrease.

Therefore, an object of the present application is to provide a switching circuit in which heat generated by transistors is small when the transistor is turned off, and a power supply system including the switching circuit.

[Effect of this disclosure]

According to the present disclosure, the amount of heat generated by the transistor in the case of turning off is small.

[Description of Embodiments of the Present Invention]

First, embodiments of the present invention will be described. In addition, at least a part of the embodiments described below may be combined arbitrarily.

(1) A switch circuit according to one aspect of the present invention is a switch circuit for a vehicle, wherein the switch circuit includes: a transistor circuit including a first main transistor having a first electrode, a second electrode, and a control an electrode, on/off between the first electrode and the second electrode is switched according to the voltage between the control electrode and the second electrode; a first surge protector connected to the transistor between the two ends of the circuit, the voltage applied to the first surge protector is maintained below the first specified voltage; and a sub-transistor is arranged between the control electrode and the second electrode of the first main transistor , and turn on when the first main transistor is off.

In one form above, for example, when the voltage of the control electrode based on the potential of the second electrode is equal to or higher than a certain voltage, the first main transistor is turned on, and the voltage of the control electrode is turned on when the potential of the second electrode is used as a reference. When the voltage is lower than a certain voltage, the first main transistor is turned off. When the first main transistor is turned off by lowering the voltage of the control electrode of the first main transistor based on a fixed potential (for example, ground potential), the sub-transistor is turned on, so the voltage based on the potential of the second electrode is The voltage of the control electrode is maintained below a certain voltage, and the first main transistor is maintained to be turned off. As a result, the amount of heat generated by the first main transistor when it is turned off is small.

In addition, when the first main transistor is turned off, the voltage of the first electrode on the basis of the fixed potential rises due to the wiring inductance of the wiring connected to the first electrode and the second electrode respectively, and the voltage of the first electrode on the basis of the fixed potential increases. The voltage of the second electrode is lowered as a reference. In this form, since the first surge protector is connected between both ends of the transistor circuit, the voltage applied between both ends of the first main transistor is maintained at a first predetermined voltage or less.

(2) In the switch circuit according to one aspect of the present invention, the transistor circuit includes a second main transistor connected to the first electrode or the second electrode of the first main transistor, and the first main transistor and The second main transistor is turned on or off at the same time.

In one manner above, the second main transistor is connected to the first main transistor, and the first main transistor and the second main transistor are turned on or off at the same time. For example, in the case where the first main transistor and the second main transistor are FETs (Field Effect Transistor, Field Effect Transistor), regarding the first main transistor and the second main transistor, there are formed between the first electrode and the second electrode respectively. diode. The first main transistor and the second main transistor can be connected so that the anodes or cathodes of the diodes of the first main transistor and the second main transistor are connected to each other. In this case, if the first main transistor and the second main transistor are off, current does not flow through the diodes of the first main transistor and the second main transistor.

(3) In the switch circuit according to one aspect of the present invention, a cutoff switch connected between the transistor circuit and the first surge protector is provided.

In the above-mentioned one manner, when the cut-off switch is turned off, no current will flow through the first surge protector. When two power storage devices are connected via a transistor circuit, a large current may flow if the positive terminal of one power storage device is mistakenly connected to the negative terminal of the other power storage device via the transistor circuit. However, if the first main transistor and the cutoff switch are off, a large current does not flow through the first surge protector 1 .

(4) The switch circuit according to one aspect of the present invention includes a switch control unit that turns on the cutoff switch before the first main transistor is turned on, and turns off the second main transistor after the first main transistor is turned on. The cutoff switch is turned off after a predetermined period of time elapses.

In the above-mentioned one aspect, since the disconnect switch is turned on before the first main transistor is turned on, and the disconnect switch is turned off after a predetermined period of time has elapsed since the first main transistor is turned off, the first surge protector functions appropriately.

(5) The switch circuit according to one aspect of the present invention includes a second surge protector connected between the transistor circuit and the first surge protector, and the voltage applied to the second surge protector maintaining the voltage below a second predetermined voltage; and a protection transistor connected to a connection node between the first main transistor and the second main transistor and between the first surge protector and the second surge protector. Connect between nodes.

In the one aspect described above, when the first main transistor and the second main transistor are, for example, FETs, a diode is formed between the first electrode and the second electrode of each of the first main transistor and the second main transistor. At this time, the anode (or cathode) of one diode is connected to the anode (or cathode) of the other diode. Therefore, when the first main transistor and the second main transistor are off, no current flows through the two diodes. When the protection transistor is turned off, as long as the voltage between the two ends of the transistor circuit is not the sum of the first specified voltage and the second specified voltage, no current will flow through the first surge protector or the second surge protector protector. Therefore, as long as the first main transistor and the protection transistor are turned off, even if the electrodes of the power storage device connected to the transistor circuit are mistaken, the first surge protector and the second surge protector will not pass through the first surge protector and the second surge protector. A large current flows through the device.

In addition, when the protection transistor is turned on, when a voltage higher than the first predetermined voltage or the second predetermined voltage is applied across the transistor circuit, a current flows through the first surge protector or the second surge protector. surge protector. At this time, a current flows through a diode formed in the first main transistor or the second main transistor.

(6) The switch circuit according to one aspect of the present invention includes a switch control unit that turns on the protection transistor before the first main transistor and the second main transistor are turned on, The protection transistor is turned off after a predetermined period has elapsed since the transistor and the second main transistor are turned off.

In one aspect described above, the protection transistor is turned on before the first main transistor and the second main transistor are turned on, and the protection transistor is turned off after a predetermined period has elapsed since the first main transistor and the second main transistor are turned off. Accordingly, the first surge protector and the second surge protector function appropriately.

(7) A power supply system according to one aspect of the present invention includes: the switching circuit described above; and two power storage devices, the positive electrodes of which are connected to the switching circuit.

In the above-described one aspect, one power storage device supplies electric power to the other power storage device via the switch circuit to charge the other power storage device. In the switching circuit, since the sub-transistor is provided, when the first main transistor is turned on, the heat generated by the first main transistor is small.

[Details of Embodiments of the Present Invention]

Next, specific examples of the switching circuit and the power supply system according to the embodiment of the present invention will be described with reference to the drawings. In addition, this invention is not limited to these examples, but is shown by a claim, and it is intended that the meaning of a claim and equality and all the changes within a range are included.

(Embodiment 1)

FIG. 1 is a schematic diagram showing the configuration of a power supply system 100 in Embodiment 1. As shown in FIG. Power supply system 100 is mounted on a vehicle. The power supply system 100 has a switching circuit 110 with a surge protection function. In the example of FIG. 1 , the switching circuit 110 with a surge protection function includes paths PS1 , PS2 , a first main transistor Tr1 , a second main transistor Tr2 , a sub-transistor Tr3 , and a first surge protector 1 .

The paths PS1 and PS2 are connected in parallel with each other. The first main transistor Tr1 and the second main transistor Tr2 are disposed on the path PS1 and connected in series with each other. The first main transistor Tr1 and the second main transistor Tr2 are N-channel FETs, and their positive directions are opposite to each other.

The first main transistor Tr1 includes a drain electrode (first electrode), a source electrode (second electrode), and a gate electrode (control electrode). The first main transistor Tr1 switches on/off of the drain electrode and the source electrode according to the control voltage between the gate electrode and the source electrode. The forward direction of the first main transistor Tr1 is the direction from the drain electrode toward the source electrode. Therefore, the drain electrode is an electrode on the positive upstream side of the first main transistor Tr1 . The second main transistor Tr2 also has the same structure as the first main transistor Tr1. The first main transistor Tr1 and the second main transistor Tr2 function as transistor circuits.

In each of the first main transistor Tr1 and the second main transistor Tr2, when the voltage of the gate electrode based on the potential of the source electrode is equal to or higher than a positive constant voltage, a current can flow between the drain electrode and the source electrode. . At this time, the first main transistor Tr1 and the second main transistor Tr2 are respectively turned on. The higher the voltage of the gate electrode based on the potential of the source electrode, the smaller the resistance value between the drain electrode and the source electrode. In addition, in each of the first main transistor Tr1 and the second main transistor Tr2, when the voltage of the gate electrode based on the potential of the source electrode is lower than a positive constant voltage, there is no gap between the drain electrode and the source electrode. Current flows. At this time, the first main transistor Tr1 and the second main transistor Tr2 are respectively turned off. The constant voltage of the first main transistor Tr1 substantially matches the constant voltage of the second main transistor Tr2.

The source electrodes of the first main transistor Tr1 and the second main transistor Tr2 are connected to each other, and the gate electrodes of the first main transistor Tr1 and the second main transistor Tr2 are respectively connected to an output end of the drive circuit 2 via gate resistors R1 and R2. twenty one. Each of the gate resistors R1 and R2 can suppress, for example, oscillation of the voltage applied to the gate electrodes of the first main transistor Tr1 and the second main transistor Tr2 .

In addition, in the example of FIG. 1 , diodes D1 and D2 are connected in parallel to the first main transistor Tr1 and the second main transistor Tr2 , respectively. The forward direction of the diode D1 is opposite to that of the first main transistor Tr1 , and the forward direction of the diode D2 is opposite to that of the second main transistor Tr2 . Such first main transistor Tr1 , second main transistor Tr2 , and diodes D1 and D2 constitute a so-called bidirectional switch. The diodes D1 and D2 are parasitic diodes of the first main transistor Tr1 and the second main transistor Tr2 respectively. The respective cathodes of the diodes D1 and D2 are connected to the drain electrodes of the first main transistor Tr1 and the second main transistor Tr2 , and the respective anodes of the diodes D1 and D2 are connected to the source electrodes of the first main transistor Tr1 and the second main transistor Tr2 . Therefore, since the anodes of the diodes D1 and D2 are connected to each other, no current flows through the diodes D1 and D2 when the first main transistor Tr1 and the second main transistor Tr2 are off.

The sub-transistor Tr3 is an NPN type bipolar transistor. The sub-transistor Tr3 is disposed between the respective gate electrodes and source electrodes of the first main transistor Tr1 and the second main transistor Tr2 . In the example of FIG. 1 , the collector of the sub-transistor Tr3 is connected to the gate electrodes of the first main transistor Tr1 and the second main transistor Tr2 via gate resistors R1 and R2 respectively, and the emitter of the sub-transistor Tr3 is connected to the first main transistor. Tr1 and the source electrode of the second main transistor Tr2.

A resistor R3 is provided between the base and emitter of the sub-transistor Tr3. In addition, the base of the sub-transistor Tr3 is grounded via the resistor R4 and the diode D3. The forward direction of the diode D3 is the direction toward the base of the sub-transistor Tr3. Therefore, the base of the sub-transistor Tr3 is connected to one end of the resistor R4, the cathode of the diode D3 is connected to the other end of the resistor R4, and the anode of the diode D3 is grounded.

In the sub-transistor Tr3 , when the voltage of the base with respect to the potential of the emitter is equal to or higher than a positive constant voltage, a current can flow between the collector and the emitter. At this time, the sub-transistor Tr3 is turned on. The higher the base voltage based on the emitter potential, the smaller the resistance between the collector and emitter. In addition, in the sub-transistor Tr3 , when the voltage of the base with respect to the potential of the emitter is lower than a positive constant voltage, no current flows between the collector and the emitter. At this time, the sub-transistor Tr3 is off. The sub-transistor Tr3 is turned on (turned on) or turned off (turned off) according to the voltage of the base based on the potential of the emitter.

A certain voltage involved in turning on and off the sub-transistor Tr3 is sufficiently lower than a certain voltage involved in turning on and off the first main transistor Tr1, and is sufficiently lower than a certain voltage involved in turning on and off the second main transistor Tr2. Voltage.

As will be described later, the sub-transistor Tr3 is turned on when the first main transistor Tr1 and the second main transistor Tr2 are off. More specifically, the sub-transistor Tr3 is turned on from the start to the end of the first main transistor Tr1 and the second main transistor Tr2 being turned off. In addition, the turn-on speed of the sub-transistor Tr3 is faster than the turn-off speed of the first main transistor Tr1 and the second main transistor Tr2 when the sub-transistor Tr3 is not provided.

The drive circuit 2 operates upon receiving a power supply voltage from the DC power supply E1. The drive circuit 2 receives a switching signal from the outside, for example, and outputs a control voltage to the gate electrodes of the first main transistor Tr1 and the second main transistor Tr2 . Thereby, ON/OFF of the first main transistor Tr1 and the second main transistor Tr2 are switched.

The drive circuit 2 is grounded. The drive circuit 2 raises the voltage of the gate electrode based on the potential of the source electrode by increasing the voltage of the gate electrode based on the potential of the source electrode for each of the first main transistor Tr1 and the second main transistor Tr2 . Accordingly, the first main transistor Tr1 and the second main transistor Tr2 are turned on. In addition, the drive circuit 2 lowers the voltage of the gate electrode based on the potential of the source electrode by lowering the voltage of the gate electrode based on the potential of the ground potential for each of the first main transistor Tr1 and the second main transistor Tr2 . Thus, the first main transistor Tr1 and the second main transistor Tr2 are turned off. The drive circuit 2 simultaneously turns on and off the first main transistor Tr1 and the second main transistor Tr2 . Here, "simultaneously" means not only that the timings of turning on and turning off are exactly the same, but also that the timings of turning on and turning off are substantially the same.

The first surge protector 1 is disposed on the path PS2, and connected in parallel to the series circuit of the first main transistor Tr1 and the second main transistor Tr2. The first surge protector 1 is an element that allows current to flow when the voltage applied to itself exceeds a predetermined value (hereinafter referred to as breakdown voltage), and is a so-called surge absorber. As the first surge protector 1, for example, a surge absorber made of a semiconductor (silicon surge absorber), a micro-gap type surge absorber, an arrester, or a varistor can be used. . The breakdown voltage of the first surge protector 1 is, for example, about 18 [V]. The voltage between the two ends of the first surge protector 1 is maintained below the breakdown voltage. The breakdown voltage is higher than the difference between the terminal voltages of the first power storage device 31 and the second power storage device 32 .

As another configuration of the first surge protector 1 , there is a configuration in which two Zener diodes are connected in series. In this case, the cathode of one Zener diode is connected to the cathode of the other Zener diode, or the anode of one Zener diode is connected to the anode of the other Zener diode. The breakdown voltages of the two Zener diodes are approximately the same.

In the example of FIG. 1 , the drain electrode of the first main transistor Tr1 is connected to the positive electrode of the first power storage device 31 , and the drain electrode of the second main transistor Tr2 is connected to the positive electrode of the second power storage device 32 . The negative electrodes of the first power storage device 31 and the second power storage device 32 are both grounded. The voltages of the first power storage device 31 and the second power storage device 32 are, for example, about 14 [V] in a fully charged state. For example, the first power storage device 31 and the second power storage device 32 are also mounted on the vehicle.

In the example of FIG. 1 , the drain electrode of the first main transistor Tr1 is connected to a connector 41 connected to one end of the line L1 . The other end of the line L1 is connected to the positive electrode of the first power storage device 31 . Similarly, the drain electrode of the second main transistor Tr2 is connected to the connector 42, and the connector 42 is connected to one end of the line L2. The other end of the line L2 is connected to the positive electrode of the second power storage device 32 . The wiring L1, L2 is a wire harness, for example. In the example of FIG. 1 , the wiring resistance and wiring inductance of the wirings L1 and L2 are equivalently shown. The wiring resistance is a resistance component of the wiring L1 or the wiring L2, and the wiring inductance is an inductance component of the wiring L1 or the wiring L2.

In addition, a plurality of loads (not shown) are installed in the vehicle, and these loads are connected to the connector 41 or the connector 42 , for example. These loads receive a power supply voltage from at least one of the first power storage device 31 and the second power storage device 32 .

Specifically, when the first main transistor Tr1 and the second main transistor Tr2 are turned on, the plurality of loads receive the power supply voltage from one of the first power storage device 31 and the second power storage device 32 . Then, when the first main transistor Tr1 and the second main transistor Tr2 are turned on, power is supplied from one of the first power storage device 31 and the second power storage device 32 to the other power storage device. electricity to charge the other power storage device. When the first main transistor Tr1 and the second main transistor Tr2 are off, power is supplied from the first power storage device 31 to the load connected to the connector 41 , and from the second power storage device 32 to the load connected to the connector 42 . power supply to the load.

Next, the operation will be described. Here, a case where the current flows from the connector 41 to the connector 42 will be representatively described. If the first main transistor Tr1 and the second main transistor Tr2 are turned on and the voltage of the first power storage device 31 is higher than the voltage of the second power storage device 32, current flows from the first power storage device 31 through the wiring L1, the first The main transistor Tr1 , the second main transistor Tr2 , and the line L2 flow to the second power storage device 32 . Thus, the second power storage device 32 is charged using the first power storage device 31 .

Then, when disconnecting between the first power storage device 31 and the second power storage device 32 , the first main transistor Tr1 and the second main transistor Tr2 are turned off.

FIG. 2 is an explanatory diagram of the operation of the switching circuit 110 in which the first surge protector 1 and the sub-transistor Tr3 are not provided. In FIG. 2, transitions of respective voltages of the gate electrodes and source electrodes of the first main transistor Tr1 and the second main transistor Tr2, and gate-source voltages of the first main transistor Tr1 and the second main transistor Tr2 are shown. and the transition of the current flowing through the first main transistor Tr1 and the second main transistor Tr2. In these transitions, the horizontal axis represents time. The respective voltages of the gate electrode and the source electrode shown in FIG. 2 are voltages based on the ground potential. The voltage between the gate and the source is the voltage of the gate based on the potential of the source electrode.

The drive circuit 2 turns on the first main transistor Tr1 and the second main transistor Tr2 by adjusting the voltage of the gate electrode to a preset voltage. At this time, the voltage of the source electrode substantially matches the terminal voltage of the first power storage device 31 based on the ground potential. In addition, since the voltage between the gate and the source is sufficiently high, the resistance values of the first main transistor Tr1 and the second main transistor Tr2 are small, and the current passes through the wiring L1, the first main transistor Tr1, the second main transistor Tr2 and the wiring L1. The line L2 flows from the first power storage device 31 to the second power storage device 32 . While the first main transistor Tr1 and the second main transistor Tr2 are on, energy is accumulated in the wiring inductances of the wirings L1 and L2.

The drive circuit 2 adjusts the voltage of the gate electrode from a set voltage to, for example, zero [V] in order to turn off the first main transistor Tr1 and the second main transistor Tr2 . In this case, the wiring inductance of the wiring L1 increases the voltage of the connector 41 based on the ground potential in order to maintain the magnitude of the current flowing in the wiring L1. In addition, when the voltage of the gate electrode is adjusted from the set voltage to zero [V], the wiring inductance of the wiring L2 makes the connector with the ground potential as a reference to maintain the magnitude of the current flowing through the wiring L2. 42 voltage reduction. As a result, the voltage of the source electrode also decreases.

The wiring inductance of the wiring L2 lowers the voltage of the source electrode until the voltage between the gate and the source becomes a positive constant voltage or more. Accordingly, the first main transistor Tr1 and the second main transistor Tr2 are kept turned on. As a result, current continues to flow through the first main transistor Tr1 and the second main transistor Tr2 , and the energy accumulated in the wiring inductance of the wirings L1 and L2 is released. Until the energy accumulated in the wiring inductance of the wiring L2 becomes zero, the voltage between the gate and the source is maintained at a constant voltage, and the currents flowing through the first main transistor Tr1 and the second main transistor Tr2 have a constant slope reduce. When the energy accumulated in the wiring inductance of the wiring L2 becomes zero, the voltage of the source electrode becomes zero [V]. Accordingly, the voltage between the gate and the source becomes zero [V], and the first main transistor Tr1 and the second main transistor Tr2 are turned off. Of course, when the first main transistor Tr1 and the second main transistor Tr2 are turned off, the current flowing through the first main transistor Tr1 and the second main transistor Tr2 is zero [A].

During the period when energy is released from the wiring inductance of the wiring L2, the voltage between the gate and the source is small, so the resistance values between the drain and the source of each of the first main transistor Tr1 and the second main transistor Tr2 are large. In addition, a large current, for example, a current exceeding 100 [A] flows through the first main transistor Tr1 and the second main transistor Tr2 . Therefore, while energy is released from the wiring inductance of the wiring L2, large power is consumed in the first main transistor Tr1 and the second main transistor Tr2, respectively, and the temperatures of the first main transistor Tr1 and the second main transistor Tr2 rise rapidly. . When the temperature of the first main transistor Tr1 and the second main transistor Tr2 is high, the functions of the first main transistor Tr1 and the second main transistor Tr2 may be degraded.

FIG. 3 is an explanatory diagram of the operation of the switching circuit 110 provided with the first surge protector 1 and the sub-transistor Tr3. In FIG. 3 , similarly to FIG. 2 , transitions of respective voltages of the gate electrodes and source electrodes of the first main transistor Tr1 and the second main transistor Tr2 , gate-to-voltage transitions of the first main transistor Tr1 and the second main transistor Tr2 are shown. The transition of the voltage between the sources and the transition of the current flowing through the first main transistor Tr1 and the second main transistor Tr2.

As in the case where the first surge protector 1 and the sub-transistor Tr3 are not provided, the drive circuit 2 turns on the first main transistor Tr1 and the second main transistor Tr2 by adjusting the gate electrode voltage to a set voltage. While the first main transistor Tr1 and the second main transistor Tr2 are on, energy is accumulated in the wiring inductances of the wirings L1 and L2.

In addition, when the first main transistor Tr1 and the second main transistor Tr2 are turned on, the voltage at the emitter of the sub-transistor Tr3 with respect to the ground potential and the terminal of the first power storage device 31 with respect to the ground potential The voltage is almost the same, and it is a positive voltage. Therefore, no current will flow through the resistor R3 through the action of the diode D3. As a result, in the sub-transistor Tr3 , the voltage of the base with respect to the potential of the emitter is zero [V], which is lower than a positive constant voltage. Therefore, when the first main transistor Tr1 and the second main transistor Tr2 are turned on, the sub-transistor Tr3 is turned off.

When the drive circuit 2 adjusts the voltage of the gate electrode from a set voltage to, for example, zero [V] in order to turn off the first main transistor Tr1 and the second main transistor Tr2, the wiring inductance of the wiring L1 is brought to the ground potential. The voltage of the connector 41 based on the reference rises, and the wiring inductance of the wiring L2 lowers the voltage of the connector 42 based on the ground potential, thereby lowering the voltage of the source electrode.

When the voltage of the source electrode drops, the voltage of the emitter of the sub-transistor Tr3 with reference to the ground potential drops. When the emitter voltage of the sub-transistor Tr3 is a negative voltage based on the ground potential and the absolute value of the voltage is greater than a certain value, the current flows through the diode D3 and the resistors R4 and R3 in sequence, and a current is generated at the resistor R3. pressure drop. Thereby, a voltage difference is generated between the emitter and the base of the sub-transistor Tr3. Thereafter, the voltage at the emitter of the sub-transistor Tr3 decreases with reference to the ground potential, and the current flowing through the resistor R3 increases, so that the magnitude of the voltage drop across the resistor R3 increases. As a result, in the sub-transistor Tr3 , the base voltage rises based on the emitter potential.

As described above, the constant voltage involved in turning off the sub-transistor Tr3 is sufficiently lower than the constant voltage involved in turning off the first main transistor Tr1 and the second main transistor Tr2 . Therefore, when the voltage of the source electrode decreases, first, the sub-transistor Tr3 is turned on. Then, a current flows from the output terminal 21 of the drive circuit 2 through the sub-transistor Tr3, the diode D2, and the wiring L2 in order, and the energy accumulated in the wiring inductance of the wiring L2 is released. While the energy accumulated in the wiring inductance of the wiring L2 is released, in the sub-transistor Tr3, the base voltage based on the potential of the emitter is low, so the resistance between the collector and the emitter in the sub-transistor Tr3 The value is large. However, since the current flowing through the sub-transistor Tr3 from the output terminal 21 of the drive circuit 2 is small, the power consumed by the sub-transistor Tr3 is small, and the temperature rise of the sub-transistor Tr3 is small.

During the period when the sub-transistor Tr3 is on, the voltage between the gate and the source is very low, so the first main transistor Tr1 and the second main transistor Tr2 are kept off, and the current flows through the first main transistor Tr1 and the second main transistor The current of Tr2 is zero [A]. When the energy accumulated in the wiring inductance of the wiring L2 becomes zero, the voltage of the source electrode becomes zero [V], and the voltage between the gate and the source becomes zero [V]. Accordingly, the first main transistor Tr1 and the second main transistor Tr2 are not turned on, and the first main transistor Tr1 and the second main transistor Tr2 are kept off. Also, when the voltage of the source electrode becomes zero [V], the voltage of the emitter of the sub-transistor Tr3 with reference to the ground potential becomes zero [V], so the sub-transistor Tr3 is turned off.

FIG. 4 is another explanatory diagram of the operation of the switching circuit 110 provided with the first surge protector 1 and the sub-transistor Tr3. FIG. 4 shows the transition of the gate-source voltage shown in FIG. 3 . In FIG. 4 , the transition of the voltage between the connectors 41 and 42 and the transition of the current flowing through the first surge protector 1 are also shown. In these transitions, the horizontal axis also represents time. The voltage between the connectors 41 and 42 is the voltage of the connector 41 based on the potential of the connector 42 .

While the gate-source voltage is high and the first main transistor Tr1 and the second main transistor Tr2 are turned on, the voltage between the connectors 41 and 42 is substantially zero [V]. When the gate-source voltage drops and the first main transistor Tr1 and the second main transistor Tr2 are turned off, as described above, the voltage of the connector 41 based on the ground potential rises, and the ground potential is taken as a reference. The voltage at connector 42 drops. Therefore, the voltage between the connectors 41 and 42 rises. When the voltage between the connectors 41 and 42 reaches the breakdown voltage of the first surge protector 1, the current flows through the wiring L1, the first surge protector 1, and the wiring L2 in sequence, and the wiring L1 , The energy accumulated in the wiring inductance of L2 is consumed. Until the energy accumulated in the wiring inductance of the wirings L1 and L2 becomes zero, the voltage between the connectors 41 and 42 is maintained at the breakdown voltage, and the current flowing through the first surge protector 1 decreases with a constant slope. When the energy stored in the wiring inductance of the wirings L1 and L2 becomes zero, the voltage between the connectors 41 and 42 is maintained at the voltage obtained by subtracting the second power storage device 32 from the terminal voltage of the first power storage device 31 . The voltage calculated from the terminal voltage.

When the current flows from the connector 42 to the connector 41, the switch circuit 110 not provided with the first surge protector 1 and the sub-transistor Tr3 and the switch circuit 110 provided with the first surge protector 1 and the sub-transistor Tr3 are connected to the The same applies to the case where the current flows from the connector 42 to the connector 41 .

If the first main transistor Tr1 and the second main transistor Tr2 are turned on and the voltage of the second power storage device 32 is higher than the voltage of the first power storage device 31, current flows from the second power storage device 32 through the wiring L2, the second power storage device 32, and the second main transistor Tr2. The second main transistor Tr2 , the first main transistor Tr1 , and the line L1 flow to the first power storage device 31 . Thus, the first power storage device 31 is charged by the second power storage device 32 .

Next, the difference between the operation when current flows from connector 42 to connector 41 and the operation when current flows from connector 41 to connector 42 will be described for switching circuit 110 without first surge protector 1 and sub-transistor Tr3 .

When the drive circuit 2 turns on the first main transistor Tr1 and the second main transistor Tr2 and the current flows from the connector 42 to the connector 41 , the voltage of the source electrode and the voltage of the second power storage device 32 based on the ground potential are equal. The terminal voltages are approximately the same. While the first main transistor Tr1 and the second main transistor Tr2 are on, energy is accumulated in the wiring inductances of the wirings L1 and L2.

When the drive circuit 2 adjusts the voltage of the gate electrode from a set voltage to, for example, zero [V] in order to turn off the first main transistor Tr1 and the second main transistor Tr2 , the wiring inductance of the wiring L2 is kept flowing. The magnitude of the current of the wiring L2 increases the voltage of the connector 42 based on the ground potential. In addition, when the voltage of the gate electrode is adjusted from the set voltage to zero [V], the wiring inductance of the wiring L1 makes the connector with the ground potential as a reference to maintain the magnitude of the current flowing through the wiring L1. The voltage of 41 is reduced. As a result, the voltage of the source electrode also decreases.

The wiring inductance of the wiring L1 lowers the voltage of the source electrode until the voltage between the gate and the source becomes a positive constant voltage or more. Accordingly, the first main transistor Tr1 and the second main transistor Tr2 are kept turned on. As a result, current continues to flow through the first main transistor Tr1 and the second main transistor Tr2, and the energy accumulated in the wiring inductance of the wirings L1 and L2 is released. Until the energy stored in the wiring inductance of the wiring L1 becomes zero, the voltage between the gate and the source is maintained at a constant voltage, and the currents flowing through the first main transistor Tr1 and the second main transistor Tr2 have a constant slope reduce. When the energy accumulated in the wiring inductance of the wiring L1 becomes zero, the voltage of the source electrode becomes zero [V]. Accordingly, the voltage between the gate and the source becomes zero [V], and the first main transistor Tr1 and the second main transistor Tr2 are turned off.

While energy is released from the wiring inductance of the wiring L1, large power is consumed in the first main transistor Tr1 and the second main transistor Tr2, respectively, and the temperatures of the first main transistor Tr1 and the second main transistor Tr2 rise rapidly. When the temperature of the first main transistor Tr1 and the second main transistor Tr2 is high, the functions of the first main transistor Tr1 and the second main transistor Tr2 may be degraded.

Next, the difference between the operation when the current flows from the connector 42 to the connector 41 and the operation when the current flows from the connector 41 to the connector 42 will be described for the switching circuit 110 provided with the first surge protector 1 and the sub-transistor Tr3.

When the first main transistor Tr1 and the second main transistor Tr2 are turned on, the emitter voltage of the sub-transistor Tr3 based on the ground potential is approximately equal to the terminal voltage of the second power storage device 32 based on the ground potential. Consistent, is a positive voltage. Therefore, no current flows through the resistor R3, and in the sub-transistor Tr3, the base voltage based on the emitter potential is zero [V], which is lower than a positive constant voltage. As a result, when the first main transistor Tr1 and the second main transistor Tr2 are on, the sub-transistor Tr3 is off.

When the drive circuit 2 adjusts the voltage of the gate electrode from a set voltage to, for example, zero [V] in order to turn off the first main transistor Tr1 and the second main transistor Tr2, the wiring inductance of the wiring L2 is brought to the ground potential. The voltage of the connector 42 based on the reference rises, and the wiring inductance of the wiring L1 lowers the voltage of the connector 41 based on the ground potential, thereby lowering the voltage of the source electrode. When the voltage of the source electrode drops, the voltage of the emitter of the sub-transistor Tr3 with reference to the ground potential drops, and the sub-transistor Tr3 is turned on.

Then, a current flows from the output terminal 21 of the drive circuit 2 through the sub-transistor Tr3, the diode D1, and the wiring L1 in order, and the energy accumulated in the wiring inductance of the wiring L1 is released. While the energy accumulated in the wiring inductance of the wiring L1 is released, the power consumed by the sub-transistor Tr3 is small, and the temperature rise of the sub-transistor Tr3 is small.

While the sub-transistor Tr3 is on, the gate-source voltage is very low, so the first main transistor Tr1 and the second main transistor Tr2 are kept off. After the energy accumulated in the wiring inductance of the wiring L1 becomes zero, the gate-source voltage becomes zero [V], and the first main transistor Tr1 and the second main transistor Tr2 are kept off. In addition, when the voltage of the source electrode becomes zero [V], the sub-transistor Tr3 is turned off.

When the gate-source voltage drops and the first main transistor Tr1 and the second main transistor Tr2 are turned off, as described above, the voltage of the connector 42 based on the ground potential rises, and the ground potential is taken as a reference. The voltage of the connector 41 drops. Therefore, the absolute value of the voltage between the connectors 41 and 42 increases. When the voltage between the connectors 41 and 42 reaches the breakdown voltage of the first surge protector 1, the current flows through the wiring L2, the first surge protector 1, and the wiring L1 in sequence, and the wiring L1 , The energy accumulated in the wiring inductance of L2 is consumed. Until the energy of the wiring inductance stored in the wiring L1, L2 becomes zero, the absolute value of the voltage between the connectors 41, 42 is maintained at the breakdown voltage, and the current flowing through the first surge protector 1 has a constant slope reduce. When the energy of the wiring inductance stored in the wiring L1, L2 becomes zero, the absolute value of the voltage between the connectors 41, 42 is maintained by subtracting the first storage voltage from the terminal voltage of the second power storage device 32. The voltage calculated from the terminal voltage of the electric device 31.

As described above, when the drive circuit 2 turns off the first main transistor Tr1 and the second main transistor Tr2, the sub-transistor Tr3 is turned on, so the voltage between the gate and the source is maintained below a certain voltage, and the first The off of the main transistor Tr1 and the second main transistor Tr2 is maintained. As a result, the heat generated by the first main transistor Tr1 and the second main transistor Tr2 when turned off is small. In addition, since the first surge protector 1 is connected between the respective drain electrodes of the first main transistor Tr1 and the second main transistor Tr2, the voltage applied between both ends of the first main transistor Tr1 and the second main transistor Tr2 is The voltage is maintained below the breakdown voltage.

(Embodiment 2)

In Embodiment 1, although a pair of the first main transistor Tr1 and the second main transistor Tr2 are provided, it is not necessary to provide both the first main transistor Tr1 and the second main transistor Tr2 . For example, when a load is provided instead of the second power storage device 32 , the second main transistor Tr2 is unnecessary.

Next, regarding Embodiment 2, differences from Embodiment 1 will be described. Since the configurations other than those described later are the same as those in Embodiment 1, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

FIG. 5 is a schematic diagram showing a part of the switch circuit 110 in the second embodiment. In the example of FIG. 5 , the first main transistor Tr1 and the first surge protector 1 are arranged on the paths PS1 and PS2 respectively, and are connected in parallel with each other. In addition, in this case, the first surge protector 1 does not need to be bidirectional, and may be a unidirectional surge protector. And, when the voltage of the first surge protector 1 (the forward voltage of the first main transistor Tr1 ) exceeds the breakdown voltage, the first surge protector 1 is turned on. In addition, the unidirectional first surge protector 1 may be connected in parallel to the first main transistor Tr1 and the second main transistor Tr2, respectively. The breakdown voltage exceeds the terminal voltage of the first power storage device 31 . In Embodiment 2, the first main transistor Tr1 functions as a transistor circuit.

In the example of FIG. 5 , the first surge protector 1 has a Zener diode whose cathode and anode are respectively connected to the drain electrode and the source electrode of the first main transistor Tr1 . In the first surge protector 1, when the voltage of the cathode based on the potential of the anode becomes the breakdown voltage, a current flows from the cathode to the anode, and the current flows between the drain and the source of the first main transistor Tr1. The voltage remains below the breakdown voltage.

The drain electrode of the first main transistor Tr1 is connected to the connector 41, and the source electrode of the first main transistor Tr1 is connected to the connector 42 and the emitter of the sub-transistor Tr3.

Switching circuit 110 in Embodiment 2 configured as described above exhibits the same effect as switching circuit 110 in Embodiment 1. FIG.

In addition, in the switch circuit 110 in Embodiment 2, no current flows from the connector 42 to the connector 41 . In addition, in the switch circuit 110 in Embodiment 2, the second main transistor Tr2 and the resistor R2 are not provided.

(Embodiment 3)

In Embodiment 2, the number of first main transistors Tr1 may be two or more.

Next, regarding Embodiment 3, differences from Embodiment 2 will be described. Since the configurations other than those described later are the same as those in Embodiment 2, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

FIG. 6 is a schematic diagram showing a part of the switch circuit 110 in the third embodiment. A plurality of paths PS1 are provided, and each path PS1 is connected to the path PS2 in parallel. A first main transistor Tr1 is provided on each path PS1. That is, the plurality of first main transistors Tr1 are connected in parallel with each other. The first surge protector 1 is connected in parallel to the plurality of first main transistors Tr1. The number of the first surge protector 1 is, for example, less than the number of the first main transistor Tr1, which is one in the example of FIG. 6 . In Embodiment 3, the plurality of first main transistors Tr1 function as a transistor circuit.

The output terminal 21 of the drive circuit 2 is connected to each gate electrode of the plurality of first main transistors Tr1 via a resistor R1. The drive circuit 2 simultaneously turns on and off the plurality of first main transistors Tr1. Here, "simultaneously" means not only that the timings of turning on and turning off are exactly the same, but also that the timings of turning on and turning off are substantially the same.

A diode D1 is connected between the drain electrode and the source electrode of each of the plurality of first main transistors Tr1 .

Switching circuit 110 in Embodiment 3 configured as described above exhibits the same effect as switching circuit 110 in Embodiment 2.

In Embodiments 2 and 3, the first main transistor Tr1 is not limited to an N-channel FET, but may be an NPN bipolar transistor or an IGBT (Insulated Gate Bipolar Transistor).

(Embodiment 4)

In Embodiment 1, the number of series circuits of the first main transistor Tr1 and the second main transistor Tr2 may be two or more.

Next, regarding Embodiment 4, differences from Embodiment 1 will be described. Since the configurations other than those described later are the same as those in Embodiment 1, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

FIG. 7 is a schematic diagram showing a part of the switch circuit 110 in the fourth embodiment. A plurality of paths PS1 are provided, and each path PS1 is connected to the path PS2 in parallel. A first main transistor Tr1 and a second main transistor Tr2 connected in series to each other are provided on each path PS1. That is, a plurality of series circuits composed of the first main transistor Tr1 and the second main transistor Tr2 are connected in parallel to each other. The first surge protector 1 is connected in parallel to the plurality of series circuits. The number of first surge protectors 1 is less than the number of the series circuits, and is one in the example of FIG. 7 . In Embodiment 4, the plurality of first main transistors Tr1 and the plurality of second main transistors Tr2 function as transistor circuits.

A diode D1 is connected between the drain electrode and the source electrode of each first main transistor Tr1. A diode D2 is connected between the drain electrode and the source electrode of each second main transistor Tr2. The respective source electrodes of the plurality of first main transistors Tr1 are connected to the emitter of the sub-transistor Tr3.

The output terminal 21 of the drive circuit 2 is connected to the respective gate electrodes of the plurality of first main transistors Tr1 via the resistor R1, and is connected to the respective gate electrodes of the plurality of second main transistors Tr2 via the resistor R2. The drive circuit 2 simultaneously turns on and off all the first main transistors Tr1 and all the second main transistors Tr2 . Here, "simultaneously" means not only that the timings of turning on and turning off are exactly the same, but also that the timings of turning on and turning off are substantially the same.

Switching circuit 110 in Embodiment 4 configured as described above exhibits the same effect as switching circuit 110 in Embodiment 1. FIG.

(Embodiment 5)

In Embodiment 1, the number of each of the first main transistor Tr1 and the second main transistor Tr2 is not limited to one.

Next, regarding Embodiment 5, differences from Embodiment 1 will be described. Since the configurations other than those described later are the same as those in Embodiment 1, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

FIG. 8 is a schematic diagram showing a part of the switch circuit 110 in Embodiment 5. As shown in FIG. The switch circuit 110 has a plurality of first main transistors Tr1 and a plurality of second main transistors Tr2. The plurality of first main transistors Tr1 are connected in parallel, and the plurality of second main transistors Tr2 are connected in parallel. A diode D1 is connected between the drain electrode and the source electrode of each first main transistor Tr1. A diode D2 is connected between the drain electrode and the source electrode of each second main transistor Tr2. In Embodiment 5, the plurality of first main transistors Tr1 and the plurality of second main transistors Tr2 function as transistor circuits.

A first surge protector 1a is connected between the drain electrode and the source electrode of the first main transistor Tr1. In the example of FIG. 8 , the first surge protector 1 a has a Zener diode whose cathode and anode are respectively connected to the drain electrode and the source electrode of the first main transistor Tr1 .

Likewise, the first surge protector 1b is connected between the drain electrode and the source electrode of the second main transistor Tr2. In the example of FIG. 8 , the first surge protector 1 b also has a Zener diode whose cathode and anode are respectively connected to the drain electrode and the source electrode of the second main transistor Tr2 .

In the Zener diode of the first surge protector 1a, when the voltage of the cathode based on the potential of the anode becomes a breakdown voltage, a current flows from the cathode to the anode. A current flows from the anode of the Zener diode of the first surge protector 1a through at least one of the plurality of diodes D2 and the first surge protector 1b.

Similarly, in the Zener diode of the first surge protector 1b, when the voltage of the cathode based on the potential of the anode becomes the breakdown voltage, a current flows from the cathode to the anode. A current flows from the anode of the Zener diode of the first surge protector 1b through at least one of the plurality of diodes D1 and the first surge protector 1a.

The respective breakdown voltages of the first surge protectors 1 a and 1 b exceed the difference between the terminal voltages of the first power storage device 31 and the second power storage device 32 .

The drive circuit 2 simultaneously turns on and off all the first main transistors Tr1 and all the second main transistors Tr2 . Here, "simultaneously" means not only that the timings of turning on and turning off are exactly the same, but also that the timings of turning on and turning off are substantially the same.

Switching circuit 110 in Embodiment 5 configured as described above exhibits the same effect as switching circuit 110 in Embodiment 1. FIG.

In addition, in Embodiment 5, the number of the first main transistor Tr1 may be the same as or different from the number of the second main transistor Tr2. In addition, the number of the first main transistor Tr1 may be one, and the number of the second main transistor Tr2 may be two or more. Furthermore, the number of the second main transistor Tr2 may be one, and the number of the first main transistor Tr1 may be two or more.

(Embodiment 6)

When the first power storage device 31 and the second power storage device 32 are installed as shown in FIG. 1 , there is a possibility that an operator may mistakenly connect the first power storage device 31 and the second power storage device 32 . For example, the positive and negative electrodes of the second power storage device 32 may be connected in reverse. That is, the negative terminal of the second power storage device 32 is connected to the connector 42 , and the positive terminal of the second power storage device 32 is grounded. Hereinafter, the state in which the positive electrode and the negative electrode are reversely connected to the first power storage device 31 or the second power storage device 32 is referred to as a reverse connection state.

In this case, the sum of the voltage of the first power storage device 31 and the voltage of the second power storage device 32 is applied to the first surge protector 1 . For example, when the voltages of the first power storage device 31 and the second power storage device 32 are 14 [V], a voltage of 28 [V] is applied to the first surge protector 1 . If the breakdown voltage of the first surge protector 1 is set to be greater than this sum, even if the second power storage device 32 is mistakenly connected as described above, current can be prevented from flowing during the operation. However, if the breakdown voltage of the first surge protector 1 is increased, the voltage generated in the first main transistor Tr1 and the second main transistor Tr2 will increase, which is not preferable.

Therefore, in Embodiment 6, an attempt is made to prevent current flow due to incorrect connection while suppressing an increase in the breakdown voltage of first surge protector 1 .

Next, regarding Embodiment 6, differences from Embodiment 1 will be described. Since the configurations other than those described later are the same as those in Embodiment 1, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

FIG. 9 is a schematic diagram showing a part of the switch circuit 110 in the sixth embodiment. Compared with the first embodiment, the switch circuit 110 with a surge protection function in FIG. 9 further includes a cutoff switch S1 as a bidirectional switch. The disconnect switch S1 is connected in series with the first surge protector 1 in the path PS2. That is, the series circuit of the first main transistor Tr1 and the second main transistor Tr2 is connected in parallel to the series circuit of the first surge protector 1 and the disconnect switch S1. In Embodiment 6, as in Embodiment 1, the first main transistor Tr1 and the second main transistor Tr2 function as transistor circuits.

In the example shown in FIG. 9 , the cutoff switch S1 includes cutoff transistors Tr4 and Tr5 . The cut-off transistors Tr4 and Tr5 are connected in series with each other, and their forward directions are opposite to each other. The cut-off transistors Tr4 and Tr5 are N-channel FETs. In addition, diodes D4 and D5 are connected in parallel to the cut-off transistors Tr4 and Tr5 , respectively. The forward directions of the shutoff transistor Tr4 and the diode D4 are opposite to each other, and the forward directions of the shutoff transistor Tr5 and the diode D5 are opposite to each other.

Therefore, the drain electrode of the cutoff transistor Tr4 is connected to one end of the first surge protector 1 on the connector 42 side, and the source electrode of the cutoff transistor Tr4 is connected to the source electrode of the cutoff transistor Tr5 . The drain electrode of the cut-off transistor Tr5 is connected to the drain electrode of the second main transistor Tr2. Diodes D4, D5 are parasitic diodes for shutting off transistors Tr4, Tr5, respectively. The cathode of the diode D4 is connected to the drain electrode of the shutdown transistor Tr4, and the anode is connected to the source electrode of the shutdown transistor Tr4. The cathode of the diode D5 is connected to the drain electrode of the shutdown transistor Tr5 , and the anode is connected to the source electrode of the shutdown transistor Tr5 .

In addition, the drain electrode of the shutdown transistor Tr4 may be connected to the drain electrode of the shutdown transistor Tr5. In this case, the source electrode of the cutoff transistor Tr4 is connected to one end of the first surge protector 1 on the connector 42 side, and the source electrode of the cutoff transistor Tr5 is connected to the drain electrode of the second main transistor Tr2 . In addition, the cut-off switch S1 only needs to be connected in series with the first surge protector 1 . Therefore, the cutoff switch S1 may be connected to one end of the first surge protector 1 on the connector 41 side.

Like the first main transistor Tr1 and the second main transistor Tr2 , the cut-off transistors Tr4 and Tr5 are each turned on when the voltage of the gate electrode based on the potential of the source electrode is equal to or higher than a positive constant voltage. Also, like the first main transistor Tr1 and the second main transistor Tr2 , each of the shutoff transistors Tr4 and Tr5 is turned off when the voltage of the gate electrode based on the potential of the source electrode is lower than a positive constant voltage. The constant voltage of the cutoff transistor Tr4 substantially coincides with the constant voltage of the cutoff transistor Tr5.

The switch circuit 110 in the sixth embodiment further includes a switch control unit 6 connected to the respective gate electrodes of the shutoff transistors Tr4 and Tr5 . The switch control unit 6 adjusts the voltage of the gate electrode on the basis of the potential of the source electrode for each of the cut-off transistors Tr4 and Tr5 . Thus, the switch control unit 6 turns on and off each of the shutoff transistors Tr4 and Tr5 .

The switch control unit 6 turns on the cutoff switch S1 by simultaneously turning on the cutoff transistors Tr4 and Tr5 , and turns off the cutoff switch S1 by simultaneously turning off the cutoff transistors Tr4 and Tr5 .

Here, "simultaneously" means not only that the timings of turning on and turning off are exactly the same, but also that the timings of turning on and turning off are substantially the same.

Even if the power supply system 100 is in reverse connection state, as long as the first main transistor Tr1 , the second main transistor Tr2 and the cut-off switch S1 are turned off, no large current will flow through the first surge protector 1 . Therefore, it is possible to use the first surge protector 1 with a smaller breakdown voltage. For example, the breakdown voltage of the first surge protector 1 may be the same breakdown voltage as that of the first embodiment. The respective breakdown voltages of the first surge protector 1 and the second surge protector 11 exceed the difference between the first power storage device 31 and the second power storage device 32 .

In addition, when the power supply system 100 is in the reverse connection state, when the cutoff switch S1 is turned off, the voltage applied to the series circuit of the first main transistor Tr1 and the second main transistor Tr2 is also applied to the cutoff switch S1 and the second main transistor Tr2. A series circuit of surge protector 1 . At this time, the voltage applied to the series circuit of the first main transistor Tr1 and the second main transistor Tr2 is divided by the disconnect switch S1 and the first surge protector 1 . Therefore, the voltage applied to the first surge protector 1 is low, so the first surge protector 1 or the cut-off switch S1 will not burn out.

The switch control unit 6 turns on the shutoff switch S1 before turning off the first main transistor Tr1 and the second main transistor Tr2 . That is, the first main transistor Tr1 and the second main transistor Tr2 are turned off while the shut-off switch S1 is turned on. Accordingly, when the first main transistor Tr1 and the second main transistor Tr2 are turned off, the first surge protector 1 functions appropriately.

The cut-off switch S1 may be always on from now on, or may be turned off when the ignition of the vehicle is stopped. However, in order to keep the cut-off switch S1 on, the switch control unit 6 needs to output a control voltage. Here, the cut-off switch S1 is a normally open type. Power may be consumed due to the output of the control voltage. Therefore, in the state where the first main transistor Tr1 and the second main transistor Tr2 are turned off, the cutoff switch S1 may also be turned off. That is, the switch control unit 6 may turn off the shutoff switch S1 after the predetermined period T1 has elapsed since the first main transistor Tr1 and the second main transistor Tr2 are turned off. FIG. 10 shows an example of a timing chart of the first main transistor Tr1 and the cutoff switch S1.

This predetermined period T1 can be set as follows. That is, a period sufficient for the current flowing through the first surge protector 1 to reach zero can be used as the predetermined period T1. In other words, the switch control unit 6 may turn off the cutoff switch S1 after the current flowing through the first surge protector 1 reaches zero. This period can be obtained in advance by, for example, experiments or simulations. By turning off the cutoff switch S1 in a state where the current is zero in this way, it is possible to avoid the occurrence of switching loss of the cutoff switch S1 .

Switching circuit 110 in Embodiment 6 configured as described above also exhibits the same effects as switching circuit 110 in Embodiment 1.

In addition, the cut-off transistors Tr4 and Tr5 are not limited to N-channel type FETs, but may be P-channel type FETs. In this case, each of the shutoff transistors Tr4 and Tr5 is turned on when the voltage of the gate electrode based on the potential of the source electrode is lower than a negative constant voltage. In addition, each of the cut-off transistors Tr4 and Tr5 is turned off when the voltage of the gate electrode based on the potential of the source electrode is equal to or higher than a negative constant voltage.

In addition, the configuration of the cutoff switch S1 may be a configuration using a bipolar transistor, a relay contact, or the like instead of the cutoff transistors Tr4 and Tr5 .

(Embodiment 7)

FIG. 11 is a schematic diagram showing a part of a switch circuit 110 in Embodiment 7. As shown in FIG.

Next, regarding Embodiment 7, differences from Embodiment 1 will be described. Since the configurations other than those described later are the same as those in Embodiment 1, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

In the switch circuit 110 with a surge protection function shown in FIG. 11 , compared with Embodiment 1, a second surge protector 11 is further provided. The second surge protector 11 is connected in series with the first surge protector 1 in the path PS2. That is, the series circuit of the first surge protector 1 and the second surge protector 11 and the series circuit of the first main transistor Tr1 and the second main transistor Tr2 are connected in parallel. In Embodiment 7, as in Embodiment 1, the first main transistor Tr1 and the second main transistor Tr2 function as transistor circuits.

Compared with Embodiment 1, the switching circuit 110 with a surge protection function in FIG. 11 is further provided with a protection transistor Tr6 and a diode D6. The protection transistor Tr6 is connected between a connection node P1 between the first main transistor Tr1 and the second main transistor Tr2 and a connection node P2 between the first surge protector 1 and the second surge protector 11 . The protection transistor Tr6 is connected in parallel with a diode D6. The forward direction of the diode D6 is opposite to that of the protection transistor Tr6. In the example of FIG. 11 , the forward direction of the protection transistor Tr6 is the direction from the connection point P2 toward the connection point P1 . The protection transistor Tr6 is an N-channel FET.

According to such a structure, the first main transistor Tr1, the protection transistor Tr6, and the diodes D1 and D6 form a bidirectional switch, and the second main transistor Tr2, the protection transistor Tr6 and the diodes D2 and D6 form a bidirectional switch. The diode D6 is a parasitic diode of the protection transistor Tr6.

Therefore, the source electrode of the protection transistor Tr6 is connected to the respective source electrodes of the first main transistor Tr1 and the second main transistor Tr2, and the drain electrode of the protection transistor Tr6 is connected to one terminal on the connector 42 side of the first surge protector 1 and the second surge protector. One end of the second surge protector 11. The other end of the second surge protector 11 is connected to the drain electrode of the second main transistor Tr2. The cathode of the diode D6 is connected to the drain of the protection transistor Tr6, and the anode is connected to the source of the protection transistor Tr6. The second surge protector 11 is configured in the same manner as the first surge protector 1 .

Like the first main transistor Tr1 and the second main transistor Tr2 , the protection transistor Tr6 is turned on when the voltage of the gate electrode based on the potential of the source electrode is equal to or higher than a positive constant voltage. In addition, like the first main transistor Tr1 and the second main transistor Tr2 , the protection transistor Tr6 is turned off when the voltage of the gate electrode based on the potential of the source electrode is lower than a positive constant voltage.

The switch circuit 110 in Embodiment 7 further includes a switch control unit 61 connected to the gate electrode of the protection transistor Tr6 . The switch control unit 61 adjusts the voltage of the gate electrode on the basis of the potential of the source electrode with respect to the protection transistor Tr6 . Thus, the switch control unit 61 turns on and off the protection transistor Tr6 .

The first power storage device 31 or the second power storage device 32 is connected while the first main transistor Tr1 , the second main transistor Tr2 , and the protection transistor Tr6 are off. At this time, as long as the voltage applied to the series circuit of the first main transistor Tr1 and the second main transistor Tr2 is not the sum of the respective breakdown voltages of the first surge protector 1 and the second surge protector 11, the Current flows through the first surge protector 1 and the second surge protector 11 . Therefore, as long as the first main transistor Tr1, the second main transistor Tr2, and the protection transistor Tr6 are turned off, even if the power supply system 100 is in the reverse connection state, the first surge protector 1 and the second surge protector will not pass through the surge protector 1 and the second surge protector. 11 A large current flows. In addition, the voltage applied to the series circuit of the first main transistor Tr1 and the second main transistor Tr2 is divided by the first surge protector 1 and the second surge protector 11 . Therefore, the voltage applied to the first surge protector 1 and the second surge protector 11 is low, so the first surge protector 1 or the second surge protector 11 does not burn out.

When the protection transistor Tr6 is turned on, when the voltage of the drain electrode of the first main transistor Tr1 based on the potential of the drain electrode of the second main transistor Tr2 becomes the breakdown voltage of the first surge protector 1 , the current flows through the first surge protector 1, the protection transistor Tr6 and the diode D2 in sequence. In the same case, when the voltage of the drain electrode of the second main transistor Tr2 based on the potential of the drain electrode of the first main transistor Tr1 becomes the breakdown voltage of the second surge protector 11, the current flows sequentially. The second surge protector 11 protects the transistor Tr6 and the diode D1.

Therefore, for example, as the first surge protector 1 and the second surge protector 11 , surge protectors having the same breakdown voltage as those in the first embodiment can be used.

The switch control unit 61 turns on the protection transistor Tr6 before turning off the first main transistor Tr1 and the second main transistor Tr2 . That is, the first main transistor Tr1 and the second main transistor Tr2 can be turned off while the protection transistor Tr6 is turned on. Accordingly, when the first main transistor Tr1 and the second main transistor Tr2 are turned off, the first surge protector 1 and the second surge protector 11 function appropriately.

When the first main transistor Tr1 and the second main transistor Tr2 are turned off in the state where the current flows from the connector 41 to the connector 42 through the first main transistor Tr1 and the second main transistor Tr2, as described above, by connecting The voltage of the connector 41 rises based on the potential of the connector 42 . When this voltage becomes the breakdown voltage of the first surge protector 1 , a current flows from the connector 41 through the first surge protector 1 , the protection transistor Tr6 , and the diode D2 in order.

Similarly, when the first main transistor Tr1 and the second main transistor Tr2 are turned off while the current flows from the connector 42 to the connector 41 through the second main transistor Tr2 and the first main transistor Tr1, as described above, The voltage of the connector 42 rises based on the potential of the connector 41 . When this voltage becomes the breakdown voltage of the second surge protector 11 , a current flows from the connector 42 through the second surge protector 11 , the protection transistor Tr6 , and the diode D1 in sequence.

Therefore, the switch circuit 110 in the seventh embodiment has the same effect as the switch circuit 110 in the first embodiment.

The protection transistor Tr6 may be kept on after being turned on, or may be turned off when the ignition of the vehicle is stopped. However, in order to keep the protection transistor Tr6 on, the switch control unit 61 needs to output a control voltage. Here, the protection transistor Tr6 is a normally-on type. Power may be consumed due to the output of the control voltage. Therefore, the protection transistor Tr6 can be turned off after a predetermined period has elapsed since the first main transistor Tr1 and the second main transistor Tr2 are turned off, similarly to the shutoff switch S1 .

In addition, the switch control part 61 may turn off the protection transistor Tr6 after the current which flows through the 1st surge protector 1 and the 2nd surge protector 11 becomes zero. Thereby, the switching loss of the protection transistor Tr6 can be reduced.

In addition, in Embodiment 7, the protection transistor Tr6 only needs to function as a switch, so it may be a bipolar transistor, an IGBT, or the like.

(Embodiment 8)

In Embodiment 1, the drain electrode of the first main transistor Tr1 is connected to the drain electrode of the second main transistor Tr2 . However, the connection of the first main transistor Tr1 and the second main transistor Tr2 is not limited to such a connection.

Next, regarding Embodiment 8, differences from Embodiment 1 will be described. Since the configurations other than those described later are the same as those in Embodiment 1, the same reference numerals are assigned to them, and detailed description thereof will be omitted.

FIG. 12 is a schematic diagram of a power supply system 100 in the eighth embodiment. In the switch circuit 110 in the eighth embodiment, the drain electrode of the first main transistor Tr1 is connected to the drain electrode of the second main transistor Tr2 . The respective source electrodes of the first main transistor Tr1 and the second main transistor Tr2 are connected to the connectors 41 and 42 . The cathode of diode D1 is connected to the cathode of diode D2 , and the anodes of diodes D1 and D2 are connected to connectors 41 and 42 , respectively. The first surge protector 1 is connected between the connectors 41 and 42 . The emitter of the sub-transistor Tr3 is connected to the source electrode of the second main transistor Tr2. Since the cathodes of the diodes D1 and D2 are connected to each other, no current flows through the diodes D1 and D2 when the first main transistor Tr1 and the second main transistor Tr2 are off. In Embodiment 8, as in Embodiment 1, the first main transistor Tr1 and the second main transistor Tr2 function as transistor circuits.

The switch circuit 110 also has a sub-transistor Tr7, a diode D7, and resistors R5 and R6. The sub-transistor Tr7 is an NPN type bipolar transistor. The emitter of the sub-transistor Tr7 is connected to the source electrode of the first main transistor Tr1, and the collector is connected to the gate electrode of the first main transistor Tr1 via the resistor R1 and to the gate electrode of Tr2 via the resistor R2. The resistor R5 is connected between the emitter and the base of the sub-transistor Tr3. The base of the sub-transistor Tr3 is also connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the cathode of the diode D7. The anode of diode D7 is grounded.

Like the sub-transistor Tr3 , the sub-transistor Tr7 is turned on when the voltage of the base with respect to the potential of the emitter is equal to or higher than a positive constant voltage. In addition, like the sub-transistor Tr3 , the sub-transistor Tr7 is turned off when the base voltage based on the emitter potential is lower than a positive constant voltage. The sub-transistor Tr7 is turned on or off according to the voltage of the base based on the potential of the emitter.

The certain voltage involved in turning on and off the sub-transistor Tr7 is also sufficiently lower than the certain voltage involved in turning on and off the first main transistor Tr1, and is sufficiently lower than the certain voltage involved in turning on and off the second main transistor Tr2. certain voltage.

When the current flows from the connector 41 to the connector 42, when the first main transistor Tr1 and the second main transistor Tr2 are turned off, the sub-transistor Tr3 functions as in the first embodiment, and the gate-source of the second main transistor Tr2 The voltage between the electrodes changes in the same manner as the voltage between the gate and the source shown in FIG. 1 . Therefore, after the first main transistor Tr1 and the second main transistor Tr2 are turned off, the turn-off of the second main transistor Tr2 is maintained.

FIG. 13 is an explanatory diagram of the operation of the switch circuit 110 . In FIG. 13 , the voltage transitions of the gate electrode and the source electrode of the first main transistor Tr1 and the transition of the gate-source voltage of the first main transistor Tr1 are shown. In these transitions, the horizontal axis represents time. The respective voltages of the gate electrode and the source electrode shown in FIG. 13 are voltages based on the ground potential. The voltage between the gate and the source is the voltage of the gate based on the potential of the source electrode.

When the drive circuit 2 turns on the first main transistor Tr1 and the second main transistor Tr2 as in the first embodiment, the voltage of the connector 41 based on the ground potential and the terminal voltage of the first power storage device 31 Roughly the same, it is a positive voltage. Therefore, no current flows through the resistor R5 through the action of the diode D7. As a result, in the sub-transistor Tr7 , the voltage of the base with respect to the potential of the emitter is zero [V], which is lower than a positive constant voltage. Therefore, when the first main transistor Tr1 and the second main transistor Tr2 are turned on, the sub-transistor Tr7 is turned off.

The drive circuit 2 adjusts the voltage of the gate electrode from a set voltage to, for example, zero [V] in order to turn off the first main transistor Tr1 and the second main transistor Tr2 as in the first embodiment. The wiring inductance of the wiring L1 increases the voltage of the connector 41 based on the ground potential until the voltage between the connectors 41 and 42 becomes the breakdown voltage of the first surge protector 1 . At this time, the emitter voltage of the sub-transistor Tr7 with reference to the ground potential is still a positive voltage, and the sub-transistor Tr7 is kept off.

When the voltage of the gate electrodes of the first main transistor Tr1 and the second main transistor Tr2 is adjusted from the set voltage to zero [V], the voltage of the source electrode of the first main transistor Tr1 rises, so the first main transistor Tr1 The gate-source voltage becomes negative. Therefore, the voltage between the gate and the source of the first main transistor Tr1 does not become more than a positive constant voltage, and the first main transistor Tr1 is kept off.

The first surge protector 1 functions in the same manner as in the first embodiment. Therefore, when the first main transistor Tr1 and the second main transistor Tr2 are turned off, a current flows through the first surge protector 1 until the energy accumulated in the wirings L1 and L2 becomes zero. The current decreases with a certain slope. When the energy accumulated in the wirings L1 and L2 becomes zero, the voltage of the source electrode of the first main transistor Tr1 drops to the terminal voltage of the first power storage device 31 based on the ground potential, and the first main transistor Tr1 The gate-source voltage rises. At this time, the voltage between the gate and the source is still negative, and the absolute value of this voltage is substantially the same as the terminal voltage of the first power storage device 31 based on the ground potential.

The operation of the switch circuit 110 when the current flows from the connector 42 to the connector 41 is the same as the operation of the switch circuit 110 when the current flows from the connector 41 to the connector 42 . When the first main transistor Tr1 and the second main transistor Tr2 are turned off when the current flows from the connector 42 to the connector 41, the sub-transistor Tr7 is the same as the sub-transistor Tr3 when the current flows from the connector 41 to the connector 42. Play a role. Therefore, after the first main transistor Tr1 and the second main transistor Tr2 are turned off, the turn-off of the first main transistor Tr1 is maintained. Here, the diode D7 and the resistors R5 and R6 correspond to the diode D3 and the resistors R3 and R4 respectively.

When the drive circuit 2 turns on the first main transistor Tr1 and the second main transistor Tr2 , the voltage at the connector 42 with respect to the ground potential substantially coincides with the terminal voltage of the second power storage device 32 and is a positive voltage. . Therefore, no current flows through resistor R3 through the action of diode D3. As a result, in the sub-transistor Tr3 , the voltage of the base with respect to the potential of the emitter is zero [V], which is lower than a positive constant voltage. Therefore, when the first main transistor Tr1 and the second main transistor Tr2 are turned on, the sub-transistor Tr7 is turned off.

The drive circuit 2 adjusts the voltage of the gate electrode from a set voltage to, for example, zero [V] in order to turn off the first main transistor Tr1 and the second main transistor Tr2 . The wiring inductance of the wiring L2 increases the voltage of the connector 42 based on the ground potential until the absolute value of the voltage between the connectors 41 and 42 becomes the breakdown voltage of the first surge protector 1 . At this time, the emitter voltage of the sub-transistor Tr3 with reference to the ground potential is still a positive voltage, and the sub-transistor Tr3 is kept off.

When the voltage of the gate electrode of the first main transistor Tr1 and the second main transistor Tr2 is adjusted from the set voltage to zero [V], the voltage of the source electrode of the second main transistor Tr2 rises, so the second main transistor Tr2 The gate-source voltage becomes negative. Therefore, the voltage between the gate and the source of the second main transistor Tr2 does not become more than a positive constant voltage, and the first main transistor Tr1 is kept off. Here, the voltage between the gate and the source of the second main transistor Tr2 is the voltage of the gate based on the potential of the source electrode.

The first surge protector 1 functions in the same manner as in the first embodiment. Therefore, when the first main transistor Tr1 and the second main transistor Tr2 are turned off, a current flows through the first surge protector 1 until the energy accumulated in the wirings L1 and L2 becomes zero. The current decreases with a certain slope. When the energy accumulated in the wirings L1 and L2 becomes zero, the voltage of the source electrode of the first main transistor Tr1 drops to the terminal voltage of the second power storage device 32 based on the ground potential, and the second main transistor Tr2 The gate-source voltage rises. At this time, the voltage between the gate and the source is still negative, and the absolute value of this voltage is substantially the same as the terminal voltage of the second power storage device 32 based on the ground potential.

The switch circuit 110 in the eighth embodiment configured as described above exhibits the same effect as the switch circuit 110 in the first embodiment.

In addition, in the eighth embodiment, as in the fourth embodiment, a plurality of series circuits composed of the first main transistor Tr1 and the second main transistor Tr2 may be connected in parallel to each other. In this case, the drain electrode of the first main transistor Tr1 is connected to the drain electrode of the second main transistor Tr2. The source electrode of each first main transistor Tr1 is connected to the emitter of the sub-transistor Tr7 , and the source electrode of each second main transistor Tr2 is connected to the emitter of the sub-transistor Tr3 .

In addition, in Embodiment 8, as described in Embodiment 5, a plurality of first main transistors Tr1 may be connected in parallel, and a plurality of second main transistors Tr2 may be connected in parallel. Furthermore, in the eighth embodiment, as shown in the sixth embodiment, the cut-off switch S1 may be connected in series to the first surge protector 1 . In addition, in the eighth embodiment, as shown in the seventh embodiment, the second surge protector 11 may be connected between one end of the first surge protector 1 on the connector 42 side and the source electrode of the second main transistor Tr2. In between, the protection transistor Tr6 is connected between the drain electrodes of the first main transistor Tr1 and the second main transistor Tr2 and one end of the first surge protector 1 on the connector 42 side. In this case, when the protection transistor Tr6 is an N-channel FET, the drain electrode of the protection transistor Tr6 is connected to the drain electrodes of the first main transistor Tr1 and the second main transistor Tr2, and the source electrode of the protection transistor Tr6 is connected to the first main transistor Tr1. One end of the surge protector 1 on the connector 42 side. Furthermore, in Embodiment 8, the sub-transistor Tr7 is not limited to an NPN type bipolar transistor, and may be an N-channel type FET.

In addition, in Embodiments 1-8, the sub-transistor Tr3 is not limited to an NPN type bipolar transistor, and may be an N-channel type FET.

The respective configurations described in the above-described embodiments and modifications can be appropriately combined as long as they do not contradict each other.

Although the present invention has been described in detail as above, the above description is illustrative in all points, and the present invention is not limited thereto. It should be understood that numerous modifications that are not illustrated can be conceived without departing from the scope of the present invention.

Label description

1, 1a, 1b First surge protector

11 Second surge protector

2 drive circuit

21 output terminal

6.61 switch control unit

31 First power storage device

32 Second power storage device

41, 42 connectors

100 power system

110 switch circuit

D1, D2, ..., D7 Diodes

E1 DC power supply

L1, L2 wiring

P1, P2 connection points

PS1, PS2 path

R1, R2, ..., R6 Resistors

S1 cut-off switch

Tr1 first main transistor

Tr2 Second main transistor

Tr3 sub transistor

Tr4, Tr5 cut off transistor

Tr6 protection transistor

Claims (7)

1. a kind of switching circuit is for motor vehicle switching circuit, wherein have：

Transistor circuit, including the first main transistor, first main transistor have first electrode, second electrode and control electricity Pole, on/off between the first electrode and the second electrode according to the coordination electrode and the second electrode it Between voltage and switch；

First Surge Protector, is connected between the both ends of the transistor circuit, will be applied to the voltage of first Surge Protector It is maintained the first assigned voltage or less；And

Associated transistor is set between the coordination electrode and the second electrode of first main transistor, described One main transistor is connected in the case of having ended.

2. switching circuit according to claim 1,

The transistor circuit includes the second master being connect with the first electrode of first main transistor or second electrode Transistor,

First main transistor and the second main transistor simultaneously turn on or end.

3. switching circuit according to claim 1 or 2,

Has the cut-out switch being connected between the transistor circuit and the first Surge Protector.

4. switching circuit according to claim 3,

Have switching controlling part, which makes the cut-out switch be connected before first main transistor conducting, The cut-out switch is set to end after specified time limit from first main transistor cut-off.

5. switching circuit according to claim 2, has：

Second Surge Protector is connected between the transistor circuit and the first Surge Protector, will be applied to second wave The voltage of surge protector is maintained the second assigned voltage or less；And

Transistor is protected, the connecting node being connected between first main transistor and the second main transistor and first wave Between connecting node between surge protector and the second Surge Protector.

6. switching circuit according to claim 5,

Has switching controlling part, which makes described before first main transistor and the conducting of the second main transistor Transistor turns are protected, described in making after specified time limit from first main transistor and the cut-off of the second main transistor Protect transistor cutoff.

7. a kind of power-supply system, has：

Switching circuit described in any one of claim 1 to 6；And

Two electrical storage devices, anode are connected to the switching circuit.